Higher-Level Awareness

The National Business Aviation Association (NBAA) Safety Committee for the first time ranks runway excursions as one of two top safety issues. On its list of 2015 NBAA Safety Focus Areas, the committee also began grouping other concerns as “specific safety hazards” and “foundations for safety.”

“The committee’s research shows [loss of control in flight (LOC-I) and runway excursions] should be primary risk-mitigation targets for all operators,” the United States-based NBAA said March 19 in announcing its third annual compilation to promote safety-focused discussion and advocacy among members and others in this segment of the aviation industry.

Through its website, magazines, conference presentations and U.S. regional safety initiatives, the association now links the following core message about runway excursions to a few simple facts backed by information that NBAA specialists accept as reliable.

“Most business aviation accidents occur in the landing phase. About one-third are runway excursions, making this the most common business aviation accident,” the association says on its website <www.nbaa.org/ops/safety/in-flight-safety/runway/runway-excursions>. “Despite efforts to improve it, the worldwide business aviation excursion accident rate has changed little over the last decade, hovering around 3.6 per million flights or some 60 percent higher than the corresponding commercial aviation rate. … Most excursions are preventable, based on well-identified risk factors, aircraft performance considerations and recommended defenses. Shifting perceptions and behaviors to increase the procedural adoption of approach and landing best practices in business aviation represents difficult challenges still ahead.”

NBAA leaders also see the runway-excursion emphasis as consistent with international aviation safety specialists’ acknowledgment of this serious and persistent threat, agreeing that some risk factors are unlike those typically faced by airlines. Steve Charbonneau, chairman of the NBAA Safety Committee and a proponent of corporate flight operational quality assurance programs (C-FOQA), says the 2015 focus areas prioritize how NBAA’s resources should be used to help improve safety industrywide.1

Heightened Concern

Both 2015 top safety issues are of highest concern to NBAA members, he said, noting, “While runway excursions are often survivable, they are also preventable … making these types of mishaps a logical target of a focused risk-reduction effort.”

The website’s explanation of runway excursions draws attention to several factors that may differentiate the risks often encountered in corporate, business and owner-flown flight operations.

“Business aviators are more likely than commercial pilots to accept tail wind approaches to facilitate routing, operate from runways of differing lengths, and land at unfamiliar airports or ones with limited means to assess and manage runway surface conditions,” NBAA said. “Consistently touching down near the aim point (1,000 ft [305 m] from the runway threshold) could help counter those challenges, but business aviation norms may impede this. Whether trying to minimize the ‘bump’ felt by passengers or lulled by landing often on runways much longer than needed, business aviators tend to carry excess speed and float into long landings.

“The average business jet touchdown point is about 1,600 ft [488 m] from the threshold, and nearly 20 percent touch down beyond 2,000 ft [610 m], well past the aim point that is the basis for predicted aircraft landing performance. The stopping distance forfeited can significantly increase the risk of excursion, especially when the runway has limited excess length or braking action is compromised.”

Charbonneau described the committee’s review of related scientific research and its risk-prioritization debate as incorporating “a rigorous, data-driven approach … based on an objective analysis that combined data trends, survey results and qualitative input from other NBAA committees, industry and regulatory partners, and members.”

The “safety focus areas” concept originally was intended to stimulate interest among people directly engaged in flight operations — especially on issues that have yet to gain wide awareness. The concept has evolved in what NBAA leaders call an effort to “provoke a meaningful discussion among colleagues within the flight department and with the corporate office [and] to guide [our] Safety Committee’s work in support of safety advocacy for the year to come, providing a useful framework for developing future NBAA resources and education efforts in the coming months. … We’re trying to educate them on those areas, as well as point out tools to help them continuously improve their safety processes and outcomes. … Everybody has different priorities [so] these are key areas where the committee believes more discussion is warranted.”

In general, publishing the 2015 NBAA Safety Focus Areas helps to increase members’ commitment to business aviation safety standards, promotes safety-enhancing discussions and encourages timely adoption of safety initiatives within flight departments and among owner-flown operations. In Charbonneau’s words, “While NBAA is committed to providing tools and resources to help operators strengthen these foundations and mitigate risk in the areas we’ve identified, we urge everyone to take steps today and examine how they can improve safety in their operations. The most effective safety efforts are proactive. Identifying and acknowledging the risks in your operations is the first step in preventing the next accident.”

One of NBAA’s magazine articles2 previously had cited research by the Flight Safety Foundation-coordinated Runway Safety Initiative in 2009 that found that failure to go around contributed to one-third of all landing-excursion accidents. In the article, Charbonneau identified what he called “strong associations with unstable approaches and long, hard and fast landings” — risk factors that can contribute to runway excursions during this phase of flight.3

In 2011, Austin Digital told AeroSafety World that, for the first time, analysts could provide operators participating in C-FOQA Centerline, a voluntary industry initiative for flight data monitoring, with detailed information concerning their risk of landing-overrun events by offering routine analysis of landing performance. The capability included monitoring threshold-crossing height, airspeed at threshold, float distance, tail wind at threshold and runway remaining when slowed to 80 kt. These events are combined to provide analysis in relation to a stabilized-landing concept.

Influential Sources

The NBAA Safety Committee partly credits a game-changing presentation at the Foundation’s 2013 Business Aviation Safety Summit (BASS) in Montreal as a strong impetus to raise consciousness of runway excursions (ASW, 7/13). Prior to that summit, business aircraft already were experiencing runway excursions at a higher rate than commercial air transports, the attendees were told by Gerard van Es, senior consultant for flight operations and safety, Air Transport Safety Institute, National Aerospace Laboratory of the Netherlands (NLR).

His study’s starting point was the runway excursion rate per million flights for three preceding calendar years, comparing airline operations with those of operators of business jets and business turboprops worldwide. “[NLR] looked at accidents, incidents, serious incidents, minor incidents, and tried to be as complete as possible. … In these three years, it’s almost a factor of two as between commercial operations and business operations,” van Es said at the time. “Differences in exposure to factors such as unstable approaches, fast landings and high tail wind landings increase the risk of an excursion.”

NLR found that such causal factors occurred, or occurred more frequently, among business aircraft operated in a business environment than those in airline operations.” He acknowledged limitations of data mining from international sources to study off-side excursions (veer-offs) and off-end excursions (overruns) with known causes. Taxiway excursions were not considered, and all events selected for the dataset involved either turbine- or turboprop–powered types with more than one engine.

Van Es noted on the positive side, however, that outcomes of business aircraft runway excursions tended to be mitigated by factors such as airport infrastructure, notably runway end safety areas and technological advances including overrun-arresting systems. He also said then that damage to aircraft occurred in about half of the excursions studied, and that the U.S. National Transportation Safety Board at the time ranked the prevention of runway excursions among its top six safety priorities within the risk domain of business aircraft operations.

Data analysis by NLR showed that relatively similar proportions of runway excursions among business operators and airlines were attributable to fast approach/touchdown, crosswind and system failure — in fact, differences in distribution of causal factors were small and similar in frequency. Flight crews’ failure to initiate a go-around was a common element, but in some cases, they were operating without a standard operating procedure for deciding whether to go around.

The key issues have been fast and high approaches, van Es emphasized (with “fast” defined as crossing the runway threshold more than 15 kt in excess of target approach speed). “We found that it was three to five times more likely, when compared to the commercial operations,” that the fast-speed condition existed in business aircraft operations.

“In business operations, we saw a range [of unstabilized approaches] as low as 1 percent, but it can also be as high as 14 percent. … There’s a very low go-around rate … after an unstabilized approach. We see roughly numbers in the 1 to 2 percent range for go-arounds in the business operations. What often happens is that the approach is unstable at 1,000 ft, but the crew manages — by speed brakes or whatever — to get it back on line at 500 ft, and for the pilot, there is no reason to abort the landing, then go into a go-around.

“We know [from flight data] and we also know from … runway excursion accidents, that business aircraft can be operated at smaller, more remote airports, airports that may be less sophisticated in their surface-monitoring system. In other words, they may lack systems in which trained observers visit the runway surface and accurately measure and report conditions. Related risk factors are less-than-optimal maintenance checks of runway surface condition, significant exposure to operations with snow on the runway and marginal snow-removal equipment for runways.”

What business aircraft operators often find is that a combination of strong gusty crosswinds with a contaminated runway sets up an unacceptable risk. “That combination is a very tricky one. … It’s not part of the official certification,” he said, and that leaves operators and pilots with only advisory material to make correct judgments about the risk level.

Charbonneau’s presentation at BASS 2013 (ASW, 6/13) proved similarly motivational for runway-excursion strategizing within the U.S. business aviation community by addressing relevant trends in unstabilized approaches.4 C-FOQA Centerline’s analysis of 2012 data, he said, had found that a “disconnected” flow of safety communication to flight crews in summer months seemed to explain higher unstable-approach rates, and the weather in North America seemed to contribute.

“It’s clear that visual approaches remain … a challenge for pilots,” he said. “Unstable approaches in visual conditions are 20 times more likely to happen than [unstable approaches] in instrument conditions. This is [the case] even when we reduce the tolerance, the gateway to achieve approach stability, from 1,000 ft to 500 ft. … Four of the top five [2012 causal] factors of unstable approach events are related to high energy states,” Charbonneau said. Analysts also identified the apparent trait of business aviation pilot culture: tailoring landing technique foremost to impress passengers. “It has been commonly accepted [for pilots] to shallow landing flares to achieve a smooth or roll-on landing, thereby trading built-in safety margins for finesse. … In the end, it comes down to a culture of normalized deviation, or accepted noncompliance, or accepted nonperformance, or perhaps even a planned-continuation bias,” he said.5

Notes

Charbonneau also is senior manager of training and standards, Altria, and chairman of the steering committee for C-FOQA Centerline.

In 2012, NBAA conducted a series of free seminars in U.S. regions highlighting runway excursion risks and mitigations, which the association then called “a perhaps underpublicized general aviation safety issue.” One of the seminar presenters from the insurance industry cited a Robert E. Breiling Associates report stating that approximately 30 percent of the accidents and incidents recorded for the U.S.-registered business jet fleet in 2011 involved runway excursions, and that for the U.S.-registered business turboprop fleet, runway excursions were involved in 24 percent of the reported accidents and incidents.

Planned-continuation bias refers to a flight crew’s unconscious cognitive inclination to continue with an original plan in spite of changing conditions.